MSC Software: Release Overview - MSC Nastran 2018 RELEASE OVERVIEW

MSC NastranTM 2018

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RELEASE OVERVIEW

Welcome to MSC Nastran 2018!With more than 50 years of industry application, MSC Nastran has widely been used by various industries to solve linear static, dynamic, nonlinear, fatigue and many other engineering problems. MSC Nastran 2018 continues the evolution of better CAE design process through implementation of new material properties for NVH studies, streamlined workflows for powertrain simulations, and new techniques for handling multilevel assemblies, all combined with more efficient solver methods. Some highlights about the new release are described in this document.

Frequency and Spatial Dependency of Materials and Properties In response to the increasing demand for lighter and stronger materials, automotive and aerospace industry leaders are taking advantage of modern composite laminates to deliver higher quality products. Some examples include laminated metals, laminated glass windscreens or layered fiber composites, commonly used as dampers to improve the noise and vibration performance of automotive vehicles and spacecraft structures.

However, it is generally difficult to capture the correct local anisotropic stiffness and damping behaviors of these materials since the values vary over a certain frequency range. To overcome this issue, MSC Nastran 2018 provides new entries that allow engineers to easily and accurately account for the frequency dependent behavior of composite materials in both Direct and Model Frequency Response solutions (SOL 108 and 111). Proper implementation of these materials provides a more efficient damping system for the overall structure.

Similarly, MSC Nastran 2018 has a new interface that allows engineers to easily define spatially dependent material properties for composite laminates. Besides safety, efficiency is another area of focus for today’s automotive industry. Modern composite materials such as carbon fibers have high strength to weight ratios and can be molded or draped into complex structural shapes, making an ideal choice for weight reduction and performance improvements of vehicles.

Implementing these laminated materials in simulations often requires users to change the thickness or orientation of certain plies. The new method in MSC Nastran 2018 makes it much simpler to define the local fiber changes and orientations in composite plies.

As seen in the next graph, accounting for frequency-dependence and spatial distribution of fiber orientations has significant impact on analysis results and enables users to accurately capture peak responses.

• Streamlined workflow- Direct export of AVL ExciteTM input (.EXB) filesfrom MSC Nastran makes data transfer much easier and faster,

• Reduced disk space - There is no need for creation and translationof large intermediate files.

• Faster options - Use of SMP parallelization methods can benefitlarge models that require calculation of higher order mass invariants.

• Accurate calculations - Obtain a full characterization of structuralresponse by including material, geometric and contact nonlinearitiesas well as preloaded conditions.

• End to durability workflow - Expand design capabilities by includingfatigue and damage responses in the process.

MSC Software: Release Overview - MSC Nastran 2018RELEASE OVERVIEW

Figure 1: Typical example of a modern NVH panel fabrication using “Glued” Steel patches with viscoelastic polymers.

Accounting for frequency-dependence and spatial distribution of fiber orientation has significant impact on analysis results.

Streamlined Workflow between MSC Nastran 2018.2 and AVL ExciteTM

MSC Nastran 2018.2 provides a direct interface with AVL ExciteTM , the most widely used MBD simulation software for design and analysis of rigid and flexible powertrains. The end to end workflow allows engineers to widen their simulation stage and include both FEA and MBD simulations to study the NVH characteristics of transmissions, car engines, and powertrain systems. MSC Nastran calculates the component modes, and mass invariants which are sent to AVL ExciteTM for further calculations of dynamic loads or system level solutions at connection points directly. The dynamic responses are imported back into MSC Nastran for an efficient data recovery step to examine the NVH and acoustic response of the structures. The integrated process between the two solvers provides up to 3 x performance gain with reduced diskspace and major cost savings for analysis of powertrain systems.

Example model Representing MSC Nastran and AVL Excite TM Results

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MSC Software: Release Overview - MSC Nastran 2018 RELEASE OVERVIEW

Modules representing different components of the model

Easier Assembly Modeling with Modules Multilevel assemblies consist of various parts and components that come from different sources and represent a section of the overall structure. Simulation and integration of these components is not easy. To overcome these issues, MSC Nastran 2018 provides new “Modules” that make substructure assembly management much easier. “Modules” are standalone sections of the MSC Nastran input file that represent a component of a full assembly (i.e. a wheel or a fender is a module that is part of the full automobile assembly). Engineers can use Modules to easily create, combine, and manage multilevel assemblies.

• Modules provide an independent process workflow, meaning that analysts can work on each module independently

• Modules are similar to part superelements without the reduction step

• Modules offer a complete range of flexibility when it comes to defining inter module connections. Manual connections range from flexible fasteners and bolts to rigid elements like RBEs.

• Automatic and semi-automatic module connections are available to the user. In the AUTO case, MSC Nastran automatically connects the grids from a Module to any coincident grids in other Modules. There is no need to be concerned with coordinate systems on these coincident points, as the solver accounts for different output coordinate systems.

• Modules may be specified along with advanced analysis features such as HPC methods, fatigue, contacts and etc.

• Results are presented in a module-by-module basis which makes it much easier for post processing purposes.

Automatic Contact Generation MSC Nastran 2018 release aims to improve existing workflows for contact analysis models. From the modeling perspective, dealing with large contact models that consist of hundreds or thousands of components is a common challenge among FEA engineers. Creation of these contact bodies in a detailed model is a time consuming and error prone task.

MSC Nastran 2018 The new Automatic Contact Generation (ACG) tool allows users to overcome these challenges by providing an efficient method to automatically create contact bodies/pairs and define the respective interaction between them. ACG is designed for a quick generation of contact models and helps engineers save time and avoid cumbersome modeling tasks.

• ACG is available for both Glued and Touching contacts.

• Users have an option to output the generated contact bodies, contact pairs and contact parameters in a separate file. The data on the file can be read into a pre/post processor for model verification purposes and further evaluation of results.

• ACG provides significant performance improvements through implementation of a good set of contact bodies and pairs inside MSC Nastran interface, reducing reliance on a pre-processor.

• Parameters such as ESet, PropSet, SeedESet and SeedGSet give user more control on elements picked to define contact regions

Contact Model Verification (2018.2) Designed to increase user productivity, MSC Nastran 2018.2 provides valuable contact verification methods that allow engineers to check the quality of contact models in early stages, thus reducing the number of design iterations. Several contact scenarios involve curved surfaces or un-intentional gaps/overlaps which may lead to incorrect results. MSC Nastran provides dedicated techniques to easily capture and correct these geometry imperfections by adjusting the position of contacting surfaces before applying the loads. These initial geometry adjustments are usually performed internally and cannot be seen in the input files. MSC Nastran 2018.2 enables engineers to review their contact models and examine these geometry changes in Patran or other GUIs. The new contact checks provide important information about the contact bodies, their initial status, and geometry conditions in various output files.

Multi Mass Configuration Complex aerospace or automotive vehicles require users to account for multiple mass configurations such as payloads, fuel conditions, passenger count, bed loads and other environmental conditions. Previously, analysts had to specify subcase dependent MPCs or perform multiple runs to simulate these mass cases. MSC Nastran 2018 provides a convenient method to account for Multiple Mass Configurations in a single run, leading to significant time savings and higher productivity.

The process is very simple and starts by defining mass increments which are then used to create a linear combination of multiple mass configurations.

MMC is supported in most MSC Nastran solutions, including linear statics and dynamics, nonlinear static and transient, aeroelastic analysis and optimization (supported with invariant mass increments).

• User can easily add various mass configurations to the base mass and run a single analysis with all mass cases.

• The mass cases are subcase selectable- A particular mass case can easily be included or removed from the analysis (similar to selecting SPCs and MPCs in a subcase).

Topology Optimization In previous versions, Stress constraints for solid element topology optimization were introduced. For the 2018 release, stress constraints are extended to support shell element topology and topometry optimization.

ACG was used to create 8 contact bodies and 14 contact pairs for this Engine Gasket model

MSC Software: Release Overview - MSC Nastran 2018RELEASE OVERVIEW

Other enhancements include identification of whirl mode type for complex Eigenvalue analysis solutions. Earlier, this process was done by plotting the mode’s whirl behavior in a post-processing software like Patran or by looking at the variation of a particular mode in a Campbell Diagram. In 2018, this feature is only available for 1D rotors defined using ROTORG bulk data entry.

High Performance Computing Analysis models that are very large in size, require an extended period of time to solve. MSC Nastran features new High Performance Computing (HPC) enhancements that enable engineers solve large problems much faster.

• Most matrix multiplication operations in MCS Nastran are handled by MPYAD module (stands for multiply and add). The 2018 release provides a completely new MPYAD module that improves matrix operations during the solving process resulting in up to 5 times faster turnaround time for many models.

• Improved performance for large NVH models through implementation of enhanced parallelization methods that make better use of SMP processing for ACMS solver. This means more threads are busy working on the solution throughout the computation process

• New Automatic Solver Selection method provides the optimal solver and parallelization configurations for each model. Previously, users had to spend some time and use trial and error methods, figuring out the best settings to run the job. The new Automatic Solver is more convenient!

1. Automatic solver will examine your model for element type, solution type, size, and memory requirements and selects the most efficient matrix or modal solver to run the job. (i.e. CASI solver is selected for solid dominated models).

2. In SOL 101 and 400, machine learning techniques have been added to predict the memory required for running the Pardiso Solver and improve on those predictions over time.

In 2018.2 the Automatic Solver has been enhanced to select the optimal number of DMP cores based on model specifications, which will significantly improve performance of SOL 108 models that have many frequencies.

Generally the goal of most toplogy optimization analysis models is to maximize structural stiffness while confining to the existing constraints (mass targets).

Since specifying a meaningful fractional mass limit is not a very easy task, most applications often recommend to create multiple runs with different mass targets. Availability of stress constraints in MSC Nastran allows users to specify a natural way for finding the optimal design without including a mass target. Inclusion of stress constraints provides a more practical design proposals that considers global stress levels in the model.

Rotordynamics In this release, several enhancements have been added to improve the efficiency of Rotordynamic analyses and provide additional output. One of the key steps for most of these simulations is generation of the Campbell diagram which demonstrates how rotor frequencies are varied with respect to rotor speed. During the analysis, the order of rotor modes may switch over the range of rotor speeds. Therefore, it is important to have a mode tracking method to identify and track a particular mode for the whole speed range. Earlier versions of MSC Nastran did not provide any mode tracking capability for Rotordynamics and users had to perform this analysis outside MSC Nastran.

In the new MSC Nastran 2018 release, mode tracking capability is added inside the MSC Nastran code and it features two methods: Numerical-based and Eigen-vector based. These new mode tracking algorithms are avilable in Direct Complex Eigenvalue Analysis (SOL 107) and Modal Complex Eigenvalue Analysis (SOL 110) solutions.Additionally MSC Nastran 2018 supports modeling of rotors in single/multi-level part superelement assemblies. This feature can significantly improve the efficiency of analysis models..

In this example, the dimensions of the clip are 100 horizontally and 80 vertically.

Minimize FRMASS s.t. stress <=100.0MPA

Scaled Performance Chart representing improvements for various models (SOL 111, 112, 200) after using the new MPYAD module

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